1. Field of the Invention
This invention relates generally to a sealing device for machines such as a rolling mill, and more particularly to an improvement in a neck sealing device for a roll, which consists in interconnecting an inside neck seal, an outside neck seal and a sleeve and providing a preventive means for preventing relative rotation between the neck seals and the sleeve so as to overcome problems encountered when a conventional sealing device is replaced.
2. Description of the Prior Art
The parts of conventional sealing devices of this type in general use exhibit looseness after extended useage and the axial movement of the sealing device increases, resulting in breakage of a lip portion and leakage of lubricating oil. In addition to the above problem, the conventional sealing device has a disadvantage in that the roll has to be suspended by the crane for replacement of the seals.
FIG. 2 shows a sealing device which has been improved to overcome the above-mentioned drawbacks. This device, too, has a disadvantage in that it requires time to be replaced, which is undesirable in view of the safety problems incurred in the replacement work.
These conventional devices will now be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a roll neck portion of a typical rolling mill.
In FIG. 1, reference numeral 1 represents a roll, whose tapered portion has a sleeve 3 secured thereto through a key 14. A bushing 6 is secured by a housing 5 in such a manner that the inner surface of the bushing 6 slides on the outer surface of the sleeve 3. A stopper 7 is secured to one end of the sleeve 3 by bolt 11. Secured by bolt 9 to one end of the housing 5 is a holder 8 which has on its outer surface a cover 10 secured thereto by a bolt 12. A gap 15 is provided between bushing 6 and stopper 7, and another gap 16 between the stopper and holder 8, for design reasons. The above is the basic arrangement of the main parts of the roll neck portion. The neck seals 21 and 22, described below, are fitted to the neck portion of roll 1 between sleeve 3 and roll 1.
FIG. 2 is an enlarged view of the neck portion showing the conventional sealing device assembled in a correct position. As shown in FIG. 2, a fixing pin 31 is secured to the other end of sleeve 3. The tapered portion of fixing pin 31 is inserted in a tapered hole 27 formed in the inside neck seal 21 to prevent relative movement between sleeve 3 and the neck seals 21 and 22. The inside neck seal 21 and the outside neck seal 22 are rigidly interconnected to prevent relative movement therebetween. A seal end plate 4 is mounted on housing 5 by means of bolt 34. A sealing lip 26 of the inside neck seal 21 and sealing lip 29 of the outside neck seal 22 are located near the central area of the cylindrical inner surface 32 of the seal and plate 4. As demonstrated in FIG. 1, since sleeve 3 and bushing 6 are in sliding engagement with each other, when assembly 2, which is mounted on the sleeve 3 of the tapered portion of roll 1, is moved outwardly in the axial direction to replace the neck seals, the components rigidly connected to bushing 6 move rearwardly relative to sleeve 3 over the length of the gap 15.
Since bushing 6 and seal end plate 4 are assembled as one piece, the relative position between the neck seals 21 and 22 and the seal end plate 4 is such that the sealing lip 29 of the outside seal 22 shifts to one end 33 of the cylindrical inner surface 32 of the seal end plate 4, as shown in FIG. 3.
Since sleeve 3 and bushing 6 are heavy, they cannot easily be moved to the position shown in FIG. 2, to replace neck seals 21 and 22, therefore, the neck seals of the roll are replaced by positioning as shown in FIG. 3.
After the neck seals 21 and 22 have been fitted, assembly 2, mounted on the sleeve 3, is assembled onto the tapered portion of roll 1. If key 14 and keyway 13, shown in FIG. 1, are out of alignment, sleeve 3 abuts the key and the components rigidly mounted on bushing 6 slide forward on sleeve 3 through the length of gaps 15 and 16 (illustrated in FIG. 1). As a result, neck seals 21 and 22 and fixing pin 31 assume their position as shown in FIG. 4. If, in this position, sleeve 3 is rotated to bring key 14 into alignment with keyway 13, relative rotation takes place between sleeve 3 and assembly 2 including neck seals 21 and 22, with the result that fixing pin 31 and tapered hole 27 become misaligned. It is, however, very difficult to bring into correct engagement simultaneously key 14 and keyway 13, and fixing pin 31 and tapered hole 27, because of the mass of sleeve 3 and bushing 6. Further, since the roller must be suspended by a crane for replacement of the seals, the assembling work must be carried out in a very unstable condition.